linux-3.3/Documentation/hwspinlock.txt

9 For example, OMAP4 has dual Cortex-A9, dual Cortex-M3 and a C64x+ DSP,
14 A generic hwspinlock framework allows platform-independent drivers to use
19 This is necessary, for example, for Inter-processor communications:
20 on OMAP4, cpu-intensive multimedia tasks are offloaded by the host to the
23 To achieve fast message-based communications, a minimal kernel support
32 A common hwspinlock interface makes it possible to have generic, platform-
38    - dynamically assign an hwspinlock and return its address, or NULL
45    - assign a specific hwspinlock id and return its address, or NULL
52    - free a previously-assigned hwspinlock; returns 0 on success, or an
53      appropriate error code on failure (e.g. -EINVAL if the hwspinlock
58    - lock a previously-assigned hwspinlock with a timeout limit (specified in
64      hardware interconnect.
66      notably -ETIMEDOUT if the hwspinlock is still busy after timeout msecs).
70    - lock a previously-assigned hwspinlock with a timeout limit (specified in
77      notably -ETIMEDOUT if the hwspinlock is still busy after timeout msecs).
82    - lock a previously-assigned hwspinlock with a timeout limit (specified in
90      notably -ETIMEDOUT if the hwspinlock is still busy after timeout msecs).
94    - attempt to lock a previously-assigned hwspinlock, but immediately fail if
99      interconnect.
101      notably -EBUSY if the hwspinlock was already taken).
105    - attempt to lock a previously-assigned hwspinlock, but immediately fail if
111      notably -EBUSY if the hwspinlock was already taken).
115    - attempt to lock a previously-assigned hwspinlock, but immediately fail if
122      notably -EBUSY if the hwspinlock was already taken).
126    - unlock a previously-locked hwspinlock. Always succeed, and can be called
132    - unlock a previously-locked hwspinlock and enable local interrupts.
140    - unlock a previously-locked hwspinlock.
148    - retrieve id number of a given hwspinlock. This is needed when an
152      Returns the hwspinlock id number, or -EINVAL if hwlock is null.
198 	 * assign a specific hwspinlock id - this should be called early
209 		return -EBUSY;
232    - to be called from the underlying platform-specific implementation, in
239    - to be called from the underlying vendor-specific implementation, in order
253  * struct hwspinlock_device - a device which usually spans numerous hwspinlocks
255  * @ops: platform-specific hwspinlock handlers
272  * struct hwspinlock - this struct represents a single hwspinlock instance
275  * @priv: private data, owned by the underlying platform-specific hwspinlock drv
299 The ->trylock() callback should make a single attempt to take the lock, and
302 The ->unlock() callback releases the lock. It always succeed, and it, too,
305 The ->relax() callback is optional. It is called by hwspinlock core while
307 a delay between two successive invocations of ->trylock(). It may _not_ sleep.